The present invention relates to an implement quick coupler latch mechanism.
Implement quick couplers are used to improve the ease of attaching an implement to the 3-point hitch of a tractor. Typically, such couplers have a U-frame with lower hooks and with latches which capture the implement pins in the lower hooks. The latches are connected via a linkage to a handle near the top of the coupler frame. The operator can manipulate the handles to open the latches to allow the implement to be detached from the quick coupler.
Most current quick couplers, including current production John Deere couplers include an L-shaped latch member. A spring on the linkage holds the linkage down, thus holding the latch in the closed position. This type of latch has an advantage in that the latches do not have to be opened prior to attaching the implement, because the implement pins can force the latches open as they enter the hooks. However, this style does not provide a positive lock on the latch to prevent it from being rotated to the open position as it relies on the force of the spring to counteract any outside forces on the latch.
Another known production John Deere coupler has a straight latch and a 2-part column. The latch pivots at one end and the column is attached to a mid point of the latch. The linkage is attached to a center pin joint area of the 2-part column. When the latch is closed, the column members are in an over-center position and act as a solid member to resist compressive loads, thus locking the latch closed. When the handle pulls the linkage upward, the linkage buckles the column, pulling the latch open. This design provided a positive lock to hold the latch closed, however, the latches had to be manually opened using the handles prior to attaching an implement. If the implement pins struck the latches in the closed position, damage could result to the parts.
In another known production John Deere coupler includes a similar column. In this design, one member of the column was roughly L-shaped and extended through the latch to provide a “trigger”. This trigger allows the implement to be attached without manually opening the latches. The implement pins contact the trigger before they contact the latches themselves. As the pins push into the coupler, the trigger buckles the column and allows the latch to move to the open position. This design combined a locking feature with the ability to attach the implement to the coupler without first opening the latches. However, the column required many components and became somewhat complex.